共查询到19条相似文献,搜索用时 125 毫秒
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流量测量是民航油料行业经营、管理必不可少的手段之一。流量参数是计算加油量的重要参数之一。目前,民航油料系统普遍采用准确度为of%的二等标准流量计对准确度为0.2%的工作流量计进行量值传递,而准确度为0.l%的二等标准流量计的溯源问题始终难于解决。为了统一民航油料流量量值、开展量值传递、满足民航油料事业的发展对流量测量的要求,中国航空油料华北公司建立了准确度为万分之五的流量标准装置。装置的组成及工作原理1.标准装置的原理图(见右图)。2.标准装置的工作原理门)被检流量计测得的体积值的确定该装置是采用比较法… 相似文献
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设计了一种自动的、可以实时检测、记录以及传输的太阳能光伏发电系统的数据检测装置,包括五个模块:电源模块、数据采集模块、数据处理模块、显示模块、无线通信模块。该装置不仅可以实时检测光伏发电组件的环境参数,而且可以把采集到的参数通过无线传输发送到远程的控制台,进行记录处理分析。 相似文献
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针对温度场测量中使用常规温度传感器引线不方便的缺点,设计了一套无引线温度测量模块。该模块具有测量精度高、无需引线、使用方便的特点。测量模块配接热电阻传感器,利用参考电阻比例测量技术,大大提高了测量稳定性。测量模块采用真空隔热蓄热技术,在-65~200℃温度范围内正常工作不少于2 h,可满足该温区真空试验罐、热压罐,或其他密闭试验装置、大空间实验装置等温度场均匀性测量的需求。 相似文献
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This paper proposes a new method for online measurement of the concentration of working fluids in absorption refrigeration systems: electrical conductivity is measured to determine the concentration of the solution. Compared with the common density-concentration method, electrical conductivity-concentration method has the same accuracy but helps to save cost when applied in absorption systems with ammonia–salt solutions. This novel method is also suitable for systems with traditional working fluids like water–lithium bromide solution. Electrical conductivities of ammonia–lithium nitrate, ammonia–sodium thiocyanate and water–lithium bromide solutions were measured between (293.15 and 333.15) K, using an Industrial Conductivity Meter. The ammonia mass fraction varied from 0.35 to 0.48 for ammonia–lithium nitrate solution and from 0.35 to 0.50 for ammonia–sodium thiocyanate solution. For water–lithium bromide solution, the mass fraction of lithium bromide was within the range of 40%–60%. The experimental data were correlated as a function of temperature and composition using the extended Casteel–Amis equation. In addition, correlations of refrigerant mass concentration as a function of electrical conductivity and temperature of the solution are proposed. 相似文献
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In this study the electrical conductivity of aluminum oxide (Al2O3), silicon dioxide (SiO2) and zinc oxide (ZnO) nanoparticles dispersed in propylene glycol and water mixture were measured in the temperature range of 0 degrees C to 90 degrees C. The volumetric concentration of nanoparticles in these fluids ranged from 0 to 10% for different nanofluids. The particle sizes considered were from 20 nm to 70 nm. The electrical conductivity measuring apparatus and the measurement procedure were validated by measuring the electrical conductivity of a calibration fluid, whose properties are known accurately. The measured electrical conductivity values agreed within +/- 1% with the published data reported by the manufacturer. Following the validation, the electrical conductivities of different nanofluids were measured. The measurements showed that electrical conductivity of nanofluids increased with an increase in temperature and also with an increase in particle volumetric concentration. For the same nanofluid at a fixed volumetric concentration, the electrical conductivity was found to be higher for smaller particle sizes. From the experimental data, empirical models were developed for three nanofluids to express the electrical conductivity as functions of temperature, volumetric concentration and the size of the nanoparticles. 相似文献
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A facility for noninvasive measurements of the electrical conductivity of liquid metals above and below the melting temperature is presented. It combines the containerless positioning method of electromagnetic levitation with the contact-less technique of inductive conductivity measurement. Contrary to the conventional measurement method, the sample is freely suspended within the measuring field and, thus, has no exactly predefined shape. This made a new theoretical basis necessary with implications on the measurement and levitation fields. Furthermore, the problem of the mutual inductive interactions between the levitation and the measuring coils had to be solved. 相似文献
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《Materials Letters》2007,61(14-15):3201-3203
The CNTs-based sensors have received considerable attention because of their outstanding properties, such as faster response, higher sensitivity, and lower operating temperature. And we expect that CNTs-based electrochemical sensors offer substantial improvements in the performance of pH sensing device. This letter reports experimental results that demonstrate the pH sensing capability of the multiwalled carbon nanotubes (MWCNTs) film by using the thermal chemical vapor deposition (thermal CVD). It was found that electronic properties of MWCNTs can be changed by the introduction of different pH value solutions. The absorption of the hydroxide in pH buffer solution changes conductivity of the MWCNTs. We observed in situ measurement of electrical conductivity by cycling solution range from acid to base. 相似文献
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Kleinberg R.L. Chew W.C. Griffin D.D. 《IEEE transactions on instrumentation and measurement》1989,38(1):22-26
A device for measuring the electrical conductivity at the surface of a large or semi-infinite body at centimeter scale has been developed. The right frequency contacting measurement uses single turn transmitter and receiver loops to generate and detect eddy currents in the material to be probed. Response is linear in conductivity over the four decades of interest in geophysical investigations. The mechanical design of the sensor makes it insensitive to temperature and pressure changes, and to accelerations, impact, and abrasion. Therefore, it is operable in remote, hostile environments such as deep boreholes 相似文献
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Machut C. Gaviot E. Codts P. Sakly S. Leclercq D. 《IEEE transactions on instrumentation and measurement》1998,47(2):398-402
This paper describes a new sensor and a new method to measure the thermal conductivity of many fluids. The principal advantage of the device is self compensation against temperature brought about by an appropriate choice of the materials. Moreover, because the sensor uses both the Peltier and Seebeck effects, measurements can be carried out with accuracy according to an average temperature increase of the device lower than 5 K. Operation of the device brings about a very low Joule power (5 mW). A coherent design rationale is formulated and the various stages in the technical development of the sensor are delineated. Several cases are discussed with a view to increasing the applicability of the method. Notable applications include thermal conductivity gauges for measuring pressures in high-vacuum systems, tank gauging for liquids featuring fire hazards, and low velocity measurements occurring in natural convection mechanisms. It is expected that the versatility of the device will result in a wide number of industrial applications 相似文献
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设计了基于USB接口的测硫仪,重点对智能控制器中的电解电流控制模块、炉温控制模块和数据采集模块进行了介绍。利用热电偶实现炉温的测量,采用具有USB接口的微处理器完成测量过程的控制和数据传输任务,并设计了高精度的信号放大和数据采集电路来保证仪器的性能,同时还对测试结果进行了精度分析。结果表明,仪器的测量精度满足国家标准。 相似文献
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当测量液体或气体流动时的温度时,温度计所测得的温度为流体的滞止温度,而不是流体的真实温度。为提高测量精度,需对所测量的温度进行修正才能得到流体的真实温度。通过液氦泵获得不同的液氦流速,来研究它对液氦测量温度的影响。描叙了实验的结果及其理论分析,并给出了如何修正测量温度而得到液氦的真实温度。 相似文献